/*
 *  FormatInformation.cpp
 *  zxing
 *
 *  Created by Christian Brunschen on 18/05/2008.
 *  Copyright 2008 ZXing authors All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "FormatInformation.h"
#include <limits>

namespace qrcode {
    int FormatInformation::FORMAT_INFO_MASK_QR = 0x5412;
    int FormatInformation::FORMAT_INFO_DECODE_LOOKUP[][2] = {
    {0x5412, 0x00},
    {0x5125, 0x01},
    {0x5E7C, 0x02},
    {0x5B4B, 0x03},
    {0x45F9, 0x04},
    {0x40CE, 0x05},
    {0x4F97, 0x06},
    {0x4AA0, 0x07},
    {0x77C4, 0x08},
    {0x72F3, 0x09},
    {0x7DAA, 0x0A},
    {0x789D, 0x0B},
    {0x662F, 0x0C},
    {0x6318, 0x0D},
    {0x6C41, 0x0E},
    {0x6976, 0x0F},
    {0x1689, 0x10},
    {0x13BE, 0x11},
    {0x1CE7, 0x12},
    {0x19D0, 0x13},
    {0x0762, 0x14},
    {0x0255, 0x15},
    {0x0D0C, 0x16},
    {0x083B, 0x17},
    {0x355F, 0x18},
    {0x3068, 0x19},
    {0x3F31, 0x1A},
    {0x3A06, 0x1B},
    {0x24B4, 0x1C},
    {0x2183, 0x1D},
    {0x2EDA, 0x1E},
    {0x2BED, 0x1F},
    };
    int FormatInformation::N_FORMAT_INFO_DECODE_LOOKUPS = 32;

    int FormatInformation::BITS_SET_IN_HALF_BYTE[] = { 
      0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4
    };
    
    int FormatInformation::numBitsDiffering(unsigned int a, unsigned int b) {
      a ^= b;
      return BITS_SET_IN_HALF_BYTE[a & 0x0F] +
      BITS_SET_IN_HALF_BYTE[(a >> 4 & 0x0F)] +
      BITS_SET_IN_HALF_BYTE[(a >> 8 & 0x0F)] +
      BITS_SET_IN_HALF_BYTE[(a >> 12 & 0x0F)] +
      BITS_SET_IN_HALF_BYTE[(a >> 16 & 0x0F)] +
      BITS_SET_IN_HALF_BYTE[(a >> 20 & 0x0F)] +
      BITS_SET_IN_HALF_BYTE[(a >> 24 & 0x0F)] +
      BITS_SET_IN_HALF_BYTE[(a >> 28 & 0x0F)];
    }

    Ref<FormatInformation> 
    FormatInformation::decodeFormatInformation(int rawFormatInfo) {
      Ref<FormatInformation> result(doDecodeFormatInformation(rawFormatInfo));
      if (result != 0) {
        return result;
      }
      return doDecodeFormatInformation(rawFormatInfo ^ FORMAT_INFO_MASK_QR);
    }
    Ref<FormatInformation> 
    FormatInformation::doDecodeFormatInformation(int rawFormatInfo) {
      // Unmask:
      int unmaskedFormatInfo = rawFormatInfo ^ FORMAT_INFO_MASK_QR;
      // Find the int in FORMAT_INFO_DECODE_LOOKUP with fewest bits differing
      int bestDifference = numeric_limits<int>::max();
      int bestFormatInfo = 0;
      for (int i = 0; i < N_FORMAT_INFO_DECODE_LOOKUPS; i++) {
        int* decodeInfo = FORMAT_INFO_DECODE_LOOKUP[i];
        int targetInfo = decodeInfo[0];
        if (targetInfo == unmaskedFormatInfo) {
          // Found an exact match
          Ref<FormatInformation> result(new FormatInformation(decodeInfo[1]));
          return result;
        }
        int bitsDifference = numBitsDiffering(unmaskedFormatInfo, targetInfo);
        if (bitsDifference < bestDifference) {
          bestFormatInfo = decodeInfo[1];
          bestDifference = bitsDifference;
        }
      }
      if (bestDifference <= 3) {
        Ref<FormatInformation> result(new FormatInformation(bestFormatInfo));
        return result;
      }
      Ref<FormatInformation> result;
      return result;
    }
    
    bool operator==(const FormatInformation &a,
                    const FormatInformation &b) {
      return &(a.errorCorrectionLevel_) == &(b.errorCorrectionLevel_) &&
      a.dataMask_ == b.dataMask_;
    }
    
    ostream& operator<<(ostream& out, const FormatInformation& fi) {
      const FormatInformation *fip = &fi;
      out << "FormatInformation @ " << (unsigned int)fip;
      return out;
    }
}
